UMECUnited Mining Exploration Commission: A group of friends playing JumpGate-- "a MMORPG that launched smoothly, breaks from fantasy character setting, emphasizes PvP, and is the first persistent world space simulator that nobody talks about." ~Scorch

It derives I think from the numvering system used in colleges/universities/educational institutions.

For some reason, each couse is given a three digit number - the first digit is usually the year of the course, and the next two digits identify the actual course.

101 is then the first course taken by first years - and is usually the introduction course for the subject.

If you were taking computer science, CS102 might be a 1st year numerical methods course, CS202 would be the 2nd year numerical methods course, and CS101 would be the Introduction to Computer Science :P